Rapid response hydraulic system



y 1966 J. 1.. GRATZMULLER 3,252,381

RAPID RESPONSE HYDRAULIC SYSTEM Filed NOV. 14, 1963 2 Sheets-Sheet 1 I6I m f M b zz F|G.l

May 24, 1966 J. L. GRATZMULLER 3,252,381

RAPID RESPONSE HYDRAULIC SYSTEM Filed Nov. 14, 1963 2 Sheets-Sheet 2United States Patent 9 Claims. (c1. 91-411 This invention relates tohydraulic systems for controlling the operation of a hydraulic motormeans such as a hydraulic jack. More particularly, the invention isconcerned with such a system wherein the operation response time iscontrolled and made as rapid as possible whereby the system can beefficiently used to operate a separate element such as, for example, anelectric circuit breaker.

In hydraulic systems utilized for control purposes and wherein ahydraulic motor means serves to provide the terminal mechanicalmovement, it has been diflicult, if not impossible to achieve rapidsystem response times and accurate repeating system operation. Morespecifically, there is a tendency in such systems, as provided in thepast, for air or other gas in the atmosphere in which the system isdisposed, to become trapped in hydraulic lines, or components, and inturn system responses and/ or repetitious operations become dependent onthe characteristics of the entrapped gasor air. When air becomes trappedin a hydraulic control system of the type with which the invention isconcerned, then the hydraulic pressures experienced within the systemduring either an activating or deactivating operation, first act tocompress the entrapped air or gas, and then after such compression, thepressures are operative to perform the particular activating ordeactivating movement. Since the amount of entrapped air or gas canvary, identical repeating operations cannot be easily achieved.Moreover, since time is required to compress the entrapped air or gas,the response times of prior systems of the type in question have beenlimited.

The problems discussed above become somewhat more severe when ahydraulic motor means, such as a hydraulic jack, is disposed at avertical level substantially above and remote from a system distributormeans incorporated to control the operation of the motor means or jack.Yet, in many instances it is desirable to locate the motor means at anupper vertical level and to locate the distributor means at a remoteposition on a lower'vertical level. Further, it is desirable toeliminate the need for large conduits passing between diflerent verticallevels by providing an auxiliary comparatively low pressure reservoir inthe vicinity of the motor means, which reservoir is adapted to receivethe fluid output of the motor means at a somewhat rapid rate, and thenempty itself by drainage at a somewhat lower rate.

The present invention is directed providing a system which is free ofthe aforesaid disadvantages, which permits difierent vertical locationsof system components, which incorporates an auxiliary reservoir meansthereby eliminating the requirement for massive conduits, and whichfurther insures complete system operation free of entrapped air or gastherein.

More specifically, the present invention is directed to the provision ofa hydraulic system incorporating a hydraulic motor means, acomparatively high volume hydraulic power circuit for operating thehydraulic motor means and a comparatively low volume hydraulic controlcircuit for controlling the operation of the hydraulic motor means bythe hydraulic power circuit, (a) which system is so constructed andarranged as to be free of entrapped air therein, and (b) which systemprovides 3,2523% Patented May 24, 1966 for rapid response times andpermits substantially identical repeating operations.

Consistent with the preceding object, the invention contemplatesutilizing an auxiliary low pressure reservoir for receiving fluiddischarged from the hydraulic motor means during deactivation thereof,which reservoir is so located and coupled in the system that, once thesystem has started satisfactory operation, air cannot pass to the motormeans or into the portion of the system coupling the reservoir with themotor means, notwithstanding the fact that system deactivation-isachieved by venting to the atmosphere. Still further, in this regard,the invention contemplates utilizing (l) a hydraulically' actuatedcontrol valve means which selectively controls the feed of the poweringhydraulic fluid into and out of the motor means, and (2) a hydrauliccontrol. circuit which operates the control valve means, but

yet is also so constructed and arranged as to operate with minor fluidflow, and as to eliminate the possibility of air or gas being entrappedtherein, notwithstanding the use of atmospheric venting of the controlcircuit for deactivating operations.

According to the invention, the aforesaid auxiliary reservoir ispositioned above the highest level of hydraulic fluid within thehydraulic motor means. The control valve means serves to selectivelycouple the hydraulic motor means either with the auxiliary reservoir ora source of fluid under pressure. The control valve means is itself, asindicated, preferably hydraulically operated and coupled in a controlcircuit having parallel branches leading from a system distributor meanswhich is located below the control valve means and below the auxiliaryreservoir. The distributor means can be positioned at some remotelocation with respect to the motor means and the control valve means,and in any event is below such means. One of the parallel branches inthe control circuit has a one-way valve therein permitting the flow offluid from the branch only in the direction to the distributor, therebyproviding for the purge of any air trapped in the control circuit.

The basic invention and preferred embodiments thereof will be betterunderstood, and objects other than those set forth above will becomeapparent, when consideration is given to the following detaileddescription. Such description makes reference to the annexed drawings,presenting preferred and illustrative embodiments of the invention.

In the drawings:

FIGURE 1 presents a schematic side view of a hydraulic systemconstructed in accordance with the present invention;

FIGURE 2 is a transverse sectional view of a control valve means whichcan be utilized in the system of FIGURE 1; and

FIGURE 3 is a schematic side view of a fragment of the system of FIGURE1, FIGURE 3 presenting modified control arrangement which can beutilized in accordance with the invention in the basic system of FIGURE1;

FIGURE 4 is a schematic view of a hydraulic system controlling aplurality of hydraulic motor means.

The system, as shown in FIGURE 1, includes a hydraulic motor means 4 inthe form of a hydraulic jack. Such jack comprises a housing 4a having apiston 5 reciprocably moveable therein. Extending upwardly from thepiston 5 is a piston rod 6 which, with reciprocal movement of the piston5, serves to control a circuit breaker St The circuit breaker St) is butillustrative of one type of device which may be contolled throughmovement, of the piston rod 6. However, the invention finds particularutility when employed for the control of the circuit breaker.

The particular mechanical connection (not shown) hetween the piston rod6 and the device which is operated by movement of such piston rod can beconventional. The invention is not concerned with the particularmechanical link utilized for coupling the motor means 4 with the deviceto be operated by the system, and accordingly, suflice it to say, thatthe motor means 4 is adapted to operate some other device, such as thecircuit breaker 50.

The hydraulic motor means 4 comprises part of a hydraulic circuitincluding a source of hydraulic fluid under pressure and an auxiliaryreservoir. As shown, the source of hydraulic fluid under pressurecomprises an accumulator 2 for supplying hydraulic fluid under apressure within a given range. The auxiliary reservoir 8, on the otherhand, takes the form of a tank which is preferably vented to theatmosphere as by a vent tube 8a. On the other hand, the auxiliaryreservoir 8 could be under some pressure interiorly, and the importantfactor is that the pressure in the auxiliary reservoir is less than thepressure of the fluid supplied from the accumulator 2.

A conduit 12 serves to connect the accumulator 2 with a control valvemeans 10, and similarly a conduit 16 serves to connect the auxiliaryreservoir 8 with the control valve means 10. Such valve means, asexplained more fully below, is provided to permit selective coupling ofthe hydraulic motor means 4 alternately with the accumulator 2 and theauxiliary reservoir 8. To this end, a coupling conduit 14 leads from theuppermost portion of the housing 4a of the jack to the control valvemeans It i The control valve means 10, as shown, is hydraulicallyactuated, but the same may take various forms. Regardless of theparticular control valve means used, it is operative in one position orcondition to supply fluid under pressure from the accumulator 2 throughthe conduit 12 and into the conduit 14. When in such position orcondition, the fluid reacts against the piston 5, thereby causing suchpiston to move vertically downward, as shown. The piston 5 preferablyreacts during this travel against a means for normally urging the pistonto an upper position, such means taking the form, for example, of thespring 7 shown in FIGURE 1. This spring is compressed between the lowerface of the piston 5 and the bottom wall of the housing 4a when thefluid under pressure is causing the piston 5 to move downwardly.

The lower position of the piston 5 can well be the activating positionthereof when the same is coupled with a separate device, such as thecircuit breaker 50. Assuming this to be true, then at some time, itwould be desired to rapidly deactivate the separate device, and in turnto permit the piston 5 to return to its upper position or deactivatedposition. To achieve this result, the control valve means 10 is operatedto a second position or condition where it dis-establishes or interruptscommunication between the conduits 12 and 14, but at the same timeestablishes communication between the conduits 14 and 16. At this time,under the action of the spring 7, the piston 5 is'urged upwardly,forcing hydraulic fluid thereabove to flow from the housing 4a into theconduit 14, through the control valve 10 and the conduit 16 into theauxiliary reservoir 8. The auxiliary reservoir 8 is dimensioned so as toeasily receive the discharged fluid from the housing 4a, and moreover,since the auxiliary reservoir 8 is vented to the atmosphere, the forceexerted by the spring 7 on the piston 5 to discharge the fluid isminimized.

The auxiliary reservoir 8 has a drain conduit 24 leading from the lowerportion thereof and extending to a sump or main reservoir 20. Theconduit 24 does not connect with the lowermost level of the auxiliaryreservoir 8, but instead is preferably positioned .such that itcommunicates with the auxiliary reservoir slightly above the lowestlevel therein. Conduit 24 permits discharged fluid to drain from theauxiliary reservoir 8 and to the sump or main reservoir 20 but, asshould be apparent, the auxiliary reservoir 8 never becomes completelyempty 4.- since the conduit 24 does not communicate with the lowestlevel thereof.

Now, bearing the foregoing ararngement in mind, it is important to note(1) that the auxiliary reservoir 8 is positioned above the highest levelof fluid in the hydraulic motor means 4, and (2) that the control valvemeans 10 is positioned below the lowest level of fluid in the auxiliaryreservoir and preferably adjacent the jack or motor means 4.

With such positioning of the auxiliary reservoir 8 and control valvemeans 10, fluid which is discharged from the jack passes upwardly. Dueto the weight of such fluid maintained in the conduit 14 and in thehousing 4a, there is always some pressure above the piston 5. Moreover,once the system has been operated the conduit 16 and the lower level ofthe auxiliary reservoir 8 are filled with fluid. This is an importantaspect of the invention, as indicated above, since as long as theconduit 16 continually contains fluid under pressure, no air or gas canbe entrapped in this conduit or in the paths leading therefrom throughthe control valve means 10. Should some air initially be trapped in thesystem described above, the same would be eliminated with the first oneor few activating and deactivating operations because the air would beexpelled with such operations through the vent tube 8a. Thus, when thecontrol valve 10 is operated to shift positions after the system hasbeen used, there is immediate fluid to fluid contact within the valvemeans 10 and between the conduits 12 and 14 or 14 and 16, as the casemay be.

The sump or main reservoir 20 referred to above has a line 21 leadingtherefrom and to the conduit 12 or essentially the accumulator 2. A pump22 is connected in such conduit so that hydraulic fluid can be returnedfrom the sump 20 under the proper pressure to the hydraulic powercircuit referred to above.

As will be noted from FIGURE 1, a line 19 leads from the sump to adistributor means 18 which takes the form of a conventional three-wayvalve. This valve is movable to alternately connect a hydraulic controlcircuit with the accumulator 2 as by the line 23, or with the sump 20 asby the line 19.

The distributor means 18 is part of the distributor or control circuitwhich operates with minor fluid flow as compared to the power circuit.The distributor or control circuit includes a pair of parallel conduitsor circuit branches 30 and 32 which feed to a common output branch 31.The output branch 31 feeds into the control valve means 10.

The control valve means, as indicated above, can take various forms, andcan include, as shown in FIGURE 1, a cylinder 25 connected to branch 31,with a piston 26 slidably mounted in the cylinder upon a piston rod 28which connects to the control valve means 10, However, the control valvemeans 10 preferably takes the form of the valve means shown in FIGURE 2and described more fully below. The significant factor to understand atthis point is that the distributor circuit or control circuit includestwo branches, one of which, namely the branch 32, has a one-way valve 34therein, which valve permits the fluid in the distributor circuit toflow only toward the distributor means 18 as shown by the arrowsadjacent the branches 30 and 32.

When the distributor 18 is positioned to couple the branch lines 30 and32 with the accumulator 2, as via the line23, then pressure is exertedby the control circuit, or specifically the fluid therein, on thecontrol valve means 10. This results in actuating the control valvemeans to one of its two operating positions or conditions. When,however, the distributor means 18 is adjusted to couple the branch lines30 and 32 with the sump 20, then the pressure on the fluid therein isessentially removed and the control valve means responds by moving toits other position or condition. However, the branch lines 30 and 32 aswell as the lines leading thereto remain completely full of hydraulicfluid, the action essentially being quite similar to that which isachieved in a barometer. For an explanation of the manner in which anautomatic purge of air from the distributor or control circuit isachieved, attention is directed to French Patent No. 1,230,514,entitled, Hydraulic Control Apparatus With Automatic Air Purge.

It is important to here note that the distributor or control circuit inthe system as well as the power circuit of the system describedinitially, both provide for venting to the atmosphere. Yet, in eachinstance the supply conduits remain completely full of fluid, therebyeliminating air or gas pockets and resulting slow and irregular responsetimes.

Referring to FIGURE 2, the hydraulic control valve means shown thereinincludes a housing a having a plurality of passageways 12, 14', 16' and31' corresponding to the conduits 12, 14, 16 and 31 to which they arerespectively coupled. The passageway 31 leads to a lower internalchamber 31a which communicates with respective piston chambers housing apiston 26a and a piston 38.

The piston 26a is coupled by a shaft 28a to an input valve controlmember 36. When fluid under pressure is applied through the passageway31, the same reacts on the piston 26a thereby lifting the valve member36 to permit fluid to flow through the passageway 12' and into thepassageway 14'. At this time, the pressure in the lower chamber 31a ofthe valve means It forces the piston 38 upwardly thereby blocking thepassageway 16'. Still, the fluid can flow around the plug end 38a of thepiston 38 which blocks the passageway 16.

When the pressure of fluid is removed from the passageway 31, the valvemember 36 moves downwardly under the action of its associated biasingspring 37 and closes communication between the passageway 12' and thepassageway 14' by blocking the valve seat 36a. Once this has occurred,the piston 5 is urged upwardly by its biasing spring 7 and the fluid inthe housing 4a is forced through the conduit 14 into the passageway 14'.This fluid reacts on the piston 26a to maintain the valve member 36seated on the valve seat 36a, but at the same time reacts against thepiston 38 to displace the same downwardly, compressing the biasingspring 39 for piston 38 and opening communication between the passageway14' and the passageway 16'.

From the above description, it should be apparent that when fluid underpressure is in the passageway 31', the conduit 12 is coupled through thevalve means 10 and the conduit 14 with the interiorof the housing 4a,and the piston 5 is accordingly moved downwardly to its lower mostposition. When the pressure on the fluid in the passageway 31 isremoved, then the piston 5 returns to its initial position with thefluid being discharged through the conduit 14 and passing to the conduit16 reacting against the pressure face of the piston 26a in the upperhousing chamber 27 (FIGURE 2) to maintain the valve member 36 in itsclosed position. In this latter regard, it is to be noted that thepressure face of the piston 26a in the chamber 27 is greater than thepressure face of the valve member 36 in such chamber, and that the valvemember 36 has openings 36a therein which permit the fluid under pressurein the passageway 12' travelling from the accumulator 2 to equalize onopposite sides of the pressure face of the valve member 36, therebypermitting the control referred to above without interference from thepower fluid under pressure.

Although the arrangement of FIGURE 2 is simple and accordingly desirablefor use in the system of FIGURE 1, a pair of control valves can be usedas the control valve means 10. In' FIGURE 3, a pair of control valves l0and 10" are shown as being coupled in the distributor or control circuitby means of the respective output lines 31 and 31". These output linesare connected with the branch lines 30 and 32, and the respective valves10 and MD are conventional valves. These valves work oppositely with onevalve 10' assuming an open position when there is pressure on the fluidin the control circuit and with the other valve 10 assuming an openposition when the pressure on the fluid in the control circuit isreduced. The operation of the valves 10 and 10" corresponds to theoperation of the control valve means 10 described above, and accordinglyfurther description of this modification appears unnecessary.

It is to be understood that even though a jack forms the preferredhydraulic motor means utilized in accordance with the invention, othermotor means can be incorporated in the system. Moreover, where a jack isused, same need not take the exact form shown in the drawings, and canbe reversed in so far as movement is connected. Regardless of theparticular motor means used, the system is readily adapted to providerapid response control for a hydraulic motor means disposed at an upperconvenient vertical level with the basic control or distributor locatedat some lower vertical level and in a remote position with respect tothe motor means and the control valve and auxiliary reservoir associatedtherewith.

Substantial advantage is obtained with the invention in connection withthe hydraulic lines or conduits required. Specifically, only one longconduit with a heavy flow capacity is needed. The remaining conduits orlines, including the return line of the power system and the supplylines of the control system, need only be of minimal size and capable ofhandling comparatively small fluid flows. Of course, it will beappreciated that the fluid flow 'in the control or distributor circuitis minor compared with the fluid flow in the power circuit.

While the invention has been shown in FIGURE 1 and described above asincluding a single motor means, the system is readily adapted to operatea plurality of motor means, for instance two hydraulic jacks 44, asshown on FIGURE 4. For this purpose, a group of control valves 1010'would be utilized and coupled in parallel to the line or conduit 12.Moreover, a separate auxiliary reservoir 8-8' would be incorporated foreach motor means with the return line from each auxiliary reservoirdraining to the sump or main reservoir 20. For common operation of thevarious motor means, a single distributor means 18 can be used. Themultiple motor means system can be operated from the same source ofhydraulic fluid under pressure (preferably a hydro-pneumatic accumulator2) notwithstanding the separate auxiliary reservoir associated with eachindividual motor means.

Having now described illustrative and preferred embodiments of thepresent invention in considerable detail, it will be appreciated thatthe objects set forth at the outset of the present specification havebeen successfully achieved.

What is claimed is:

l. In a hydraulic system of the type including a hydraulic circuithaving therein hydraulic motor means, a source of hydraulic fluid underpressure within a given range, a main reservoir positioned below thelowest level of fluid in said motor means, an auxiliary reservoir undera pressure less than the pressures within said given range andcommunicating with said main reservoir and hydraulically actuatedcontrol means for selectively coupling said hydraulic motor meansalternatively with said source of hydraulic fluid and said auxiliaryreservoir, the improvement comprising:

(a) said auxiliary reservoir being positioned above the highest level offluid in said motor means,

(b) a distributor circuit including distributor means positioned belowsaid hydraulic motor means for selectively coupling said control valvemeans with said source of hydraulic fluid to actuate said control valvemeans, and

(c) said control valve means being positioned above said distributormeans and below the lowest level of fluid in said auxiliary reservoir,whereby said hydraulic motor means, said control valve means and theportion of said hydraulic circuit between said auxiliary reservoir andsaid control valve means remain filled with hydraulic fluid regardlessof the selective coupling of said motor means with said auxiliaryreservoir and said source of hydraulic fluid.

2. The improvement defined in claim 1, wherein said distributor circuitincludes a pair of parallel branches, one of which branches has aone-way valve therein for permitting the flow of liquid within said onebranch only toward said distributor means.

3. The improvement defined in claim 1 and further including means forpassing fluid from said ma-in reservoir to said source of fluid underpressure.

4. The improvement defined in claim 3 wherein said auxiliary reservoirhas an output line leading to said main reservoir, said output linebeing in communication with said auxiliary reservoir above the lowestlevel therein.

5. The improvement defined in claim 1, wherein said hydnaulicallyactuated control means comprises a pair of hydraulically operated valvescoupled in said distributor circuit for common operation by saiddistributor means.

6. The improvement defined in claim 1 wherein said distributor means iscoupled with said source of hydraulic fluid under pressure and operativeto exert pressure on the fluid in said distributor circuit transmittedfrom said source.

7. The improvement defined in claim 1 wherein said distributor means isoperative to alternately selectively couple said distributor circuitwith said main reservoir and said source of hydraulic fluid underpressure.

8. A hydraulic system comprising a plurality of hydraulic motor means,fluid supply means for delivering hydraulic fluid under pressure withina given range, a plurality of reservoirs under pressures less than thepressures within said given range, said reservoirs each being coupledrespectively with a different one of said hydraulic motor means, saidreservoirs being positioned above the highest level of fluidrespectively in the hydraulic motor means with which said reservoirs arerespectively coupled, control valve means for selectively coupling saidhydraulic motor means with said fluid supply means and said reservoirs,hydraulic control circuit means coupled with said control valve meansand including distributor means positioned below said hydraulic motormeans and said reservoirs for selectively actuating said control valvemeans.

9. A hydraulic system including a hydraulic jack having a hydraulicfluid inlet in the upper portion thereof, a circuit breaker operated bysaid jack, a source of hydraulic fluid under pressure, an auxiliary lowpressure reservoir positioned above said fluid inlet in said jack, amain reservoir for receiving fluid from said auxiliary reservoir undergravity flow, hydraulically actuated control valve means positionedabove said main reservoir and below said auxiliary reservoir forselectively coupling said jack alternatively with said source ofhydraulic fluid and said auxiliary reservoir, hydraulic control circuitmeans coupled to said control valve means and including distributormeans positioned below said jack and said control valve means forselectively coupling said control circuit means with said source ofhydraulic fluid to actuate said control valve means.

References Cited by the Examiner UNITED STATES PATENTS 2,608,986 9/ 1952Stephens 914l4 2,948,262 8/1960 Gratzmuller 9146l 2,972,337 2/1961Coggeshall et al 1- 91461 3,119,308 1/1964 Dantowitz 91-461 SAMUELLEVINE, Primary Examiner.

FRED E. ENGELTHALER, Examiner.

P. E. MASLOUSKY, Assistant Examiner.

1. IN A HYDRAULIC SYSTEM OF THE TYPE INCLUDING A HYDRAULIC CIRCUITHAVING THEREIN HYDRAULIC MOTOR MEANS, A SOURCE OF HYDRAULIC FLUID UNDERPRESSURE WITHIN A GIVEN RANGE, A MAIN RESERVOIR POSITIONED BELOW THELOWEST LEVEL OF FLUID IN SAID MOTOR MEANS, AN AUXILIARY RESERVOIR UNDERA PRESSURE LESS THAN THE PRESSURES WITHIN SAID GIVEN RANGE ANDCOMMUNICATING WITH SAID MAIN RESERVOIR AND HYDRAULICALLY ACTUATEDCONTROL MEANS FOR SELECTIVELY COUPLING SAID HYDRAULIC MOTOR MEANSALTERNATIVELY WITH SAID SOURCE OF HYDRAULIC FLUID AND SAID AUXILIARYRESERVOIR, THE IMPROVEMENT COMPRISING: (A) SAID AUXILIARY RESERVOIRBEING POSITIONED ABOVE THE HIGHEST LEVEL OF FLUID IN SAID MOTOR MEANS,(B) A DISTRIBUTOR CIRCUIT INCLUDING DISTRIBUTOR MEANS POSITIONED BELOWSAID HYDRAULIC MOTOR MEANS FOR SELECTIVELY COUPLING SAID CONTROL VALVEMEANS WITH SAID SOURCE OF HYDRAULIC FLUID TO ACTUATE SAID CONTROL VALVEMEANS, AND (C) SAID CONTROL VALVE MEANS BEING POSITIONED ABOVE SAIDDISTRIBUTOR MEANS AND BELOW THE LOWEST LEVEL OF FLUID IN SAID AUXILIARYRESERVOIR, WHEREBY SAID HYDRAULIC MOTOR MEANS, SAID CONTROL VALVE MEANSAND THE PORTION OF SAID HYDRAULIC CIRCUIT BETWEEN SAID AUXILIARYRESERVOIR AND SAID CONTROL VALVE MEANS REMAIN FILLED WITH HYDRAULICFLUID REGARDLESS OF THE SELECTIVE COUPLING OF SAID MOTOR MEANS WITH SAIDAUXILIARY RESERVOIR AND SAID SOURCE OF HYDRAULIC FLUID.